Sprenkeler David, Hersbach Ferry, Oomen Ad, van Ofwegen-Hanekamp Clara, Meine Mathias
Department of Cardiology, Division of Heart & Lungs, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, the Netherlands.
Department of Cardiology, Diakonessenhuis, Bosboomstraat 1, 3582 KE Utrecht, the Netherlands.
Eur Heart J Case Rep. 2025 Mar 15;9(3):ytaf131. doi: 10.1093/ehjcr/ytaf131. eCollection 2025 Mar.
Implantable cardioverter defibrillators (ICDs) have been proven to reduce the risk of sudden cardiac death from ventricular tachyarrhythmias. However, ICDs can sometimes induce malignant arrhythmias. We describe a case of ventricular fibrillation triggered by an automatic atrial threshold search.
A 72-year-old man presented after a syncopal episode. His medical history included moderate aortic regurgitation and a symptomatic second-degree atrioventricular (AV) block, for which he received a dual-chamber pacemaker in 2013, later upgraded to a CRT-D due to pacing-induced heart failure. ICD interrogation revealed an episode of ventricular fibrillation terminated by a shock. The arrhythmia started directly after an atrial threshold search. Extensive work-up did not reveal a cause of the arrhythmia, therefore, we considered it most likely that the atrial threshold test triggered the ventricular fibrillation. Atrial Capture Management was disabled, and the patient was discharged. No further ventricular arrhythmias or ICD therapies were observed.
Automatic threshold measurement algorithms are intended to ensure effective myocardial capture and enhance safety but can sometimes inadvertently cause arrhythmias. The underlying mechanism in this case may be related to the switch from biventricular to right ventricular (RV)-only pacing during Atrial Capture Management, which increases dispersion in repolarization, facilitating early afterdepolarizations and triggering polymorphic tachycardias. Notably, newer ICD models mitigate this risk by maintaining biventricular pacing during this test. This case underscores the need for careful programming and monitoring of ICD algorithms.
植入式心脏复律除颤器（ICD）已被证明可降低室性快速心律失常导致的心源性猝死风险。然而，ICD有时会诱发恶性心律失常。我们描述一例由自动心房阈值搜索引发心室颤动的病例。
一名72岁男性在晕厥发作后前来就诊。他的病史包括中度主动脉瓣反流和有症状的二度房室传导阻滞，为此他于2013年接受了双腔起搏器植入，后来因起搏诱发的心力衰竭升级为CRT-D。ICD程控显示一次心室颤动发作被电击终止。心律失常在心房阈值搜索后直接开始。全面检查未发现心律失常的原因，因此，我们认为最有可能是心房阈值测试触发了心室颤动。心房夺获管理功能被禁用，患者出院。未观察到进一步的室性心律失常或ICD治疗。
自动阈值测量算法旨在确保有效的心肌夺获并提高安全性，但有时可能会无意中导致心律失常。本例的潜在机制可能与心房夺获管理期间从双心室起搏转换为仅右心室（RV）起搏有关，这会增加复极离散度，促进早期后除极并触发多形性心动过速。值得注意的是，新型ICD型号通过在该测试期间维持双心室起搏来降低这种风险。该病例强调了对ICD算法进行仔细程控和监测的必要性。
